U.S. patent number 10,865,503 [Application Number 16/324,076] was granted by the patent office on 2020-12-15 for sawtooth wire for rollers of spinning preparation machines.
This patent grant is currently assigned to TRUETZSCHLER GMBH & CO. KG. The grantee listed for this patent is Truetzschler GmbH & Co. KG.. Invention is credited to Peter Gabler, Friedrich Haarer.
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United States Patent |
10,865,503 |
Gabler , et al. |
December 15, 2020 |
Sawtooth wire for rollers of spinning preparation machines
Abstract
A sawtooth wire in which each tooth has a tooth tip and a tooth
front having a first segment extending from the tooth tip towards a
tooth side remote from a bearing edge and towards the tooth back
and merging into a concave second segment that merges into a third
segment extending towards the tooth side and merging into a concave
fourth segment. that merges into a tooth back of the next tooth.
The length of a tangent from a turning point of the second segment
to the tooth side is greater than or equal to half the spacing
between the tooth tip and the tooth side.
Inventors: |
Gabler; Peter
(Ebhausen-Rotfelden, DE), Haarer; Friedrich
(Neubulach, DE) |
Applicant: |
Name |
City |
State |
Country |
Type |
Truetzschler GmbH & Co. KG. |
Moenchengladbach |
N/A |
DE |
|
|
Assignee: |
TRUETZSCHLER GMBH & CO. KG
(Moenchengladbach, DE)
|
Family
ID: |
1000005243491 |
Appl.
No.: |
16/324,076 |
Filed: |
July 7, 2017 |
PCT
Filed: |
July 07, 2017 |
PCT No.: |
PCT/EP2017/067085 |
371(c)(1),(2),(4) Date: |
February 07, 2019 |
PCT
Pub. No.: |
WO2018/028904 |
PCT
Pub. Date: |
February 15, 2018 |
Prior Publication Data
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|
|
Document
Identifier |
Publication Date |
|
US 20190169769 A1 |
Jun 6, 2019 |
|
Foreign Application Priority Data
|
|
|
|
|
Aug 8, 2016 [DE] |
|
|
10 2016 114 622 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D01G
15/88 (20130101) |
Current International
Class: |
D01G
15/88 (20060101) |
Field of
Search: |
;19/114 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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204738066 |
|
Nov 2014 |
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CN |
|
8709898 |
|
Dec 1988 |
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DE |
|
99/38661 |
|
Aug 1999 |
|
WO |
|
Other References
International Search Report for PCT/EP2017/067085 dated Oct. 24,
2017. cited by applicant .
Written Opinion for PCT/EP2017/067085. cited by applicant.
|
Primary Examiner: Hurley; Shaun R
Assistant Examiner: Nguyen; Bao-Thieu L
Attorney, Agent or Firm: FisherBroyles, LLP Kinberg;
Robert
Claims
The invention claimed is:
1. A sawtooth wire adapted to be applied in a coil-like manner to a
spinning room preparation machine roll along an outer periphery of
the spinning room preparation machine roll and approximately
transversely with respect to a rotational axis of the spinning room
preparation machine roll, comprising: a tooth base having a bearing
edge, which extends along a longitudinal extent of the sawtooth
wire, the tooth base having a tooth side remote from and opposite
to the bearing edge; and a row of teeth located on the tooth side
of the tooth base, wherein when the sawtooth wire is stretched out:
the row of teeth extends along the longitudinal extent of the
sawtooth wire; teeth of the row of teeth are arranged one after
another in a row along the longitudinal extent of the sawtooth wire
so that they project from the tooth side perpendicularly to the
longitudinal extent of the sawtooth wire; and each tooth includes:
a tooth tip which points along the longitudinal extent of the
sawtooth wire in a same direction as the tooth tips of the other
teeth of the row of teeth and lies parallel to the tooth side or
encloses an acute angle with the tooth side; a tooth back behind
the tooth tip; and a tooth front including first, second, third and
fourth segments, wherein starting from the tooth tip of the tooth:
the first segment extends at an acute angle towards the tooth side
and towards the associated tooth back of the tooth, and merges into
the second segment; the second segment is concave and adjoins an
end of the first segment remote from the tooth tip, wherein an end
of the second segment remote from the first segment points at an
acute angle with respect to the tooth side towards the tooth side
and away from the associated tooth back, and merges into the third
segment; the third segment adjoins the end of the second segment
remote from the first segment, wherein the third segment extends
towards the tooth side and away from the associated tooth back and
merges into the fourth segment; and the fourth segment is concave
and adjoins an end of the third segment remote from the second
segment, wherein an end of the fourth segment remote from the third
segment points in the direction of the longitudinal extent of the
sawtooth wire and away from the associated tooth back, and wherein
the end of the fourth segment remote from the third segment borders
upon the tooth back of the subsequent tooth in the row of teeth;
wherein the second segment has a turning point at which a tangent
applied to the second segment runs perpendicularly to the tooth
side, a length of the tangent from the turning point to the tooth
side is greater than or equal to half of a spacing between the
associated tooth tip and the tooth side, and a ratio between the
length of the tangent and the spacing is 4:5.
2. The sawtooth wire according to claim 1, wherein the second
segment corresponds to a part of a perimeter of an ellipse.
3. The sawtooth wire according to claim 2, wherein the ellipse is a
circle having a predetermined radius.
4. The sawtooth wire according to claim 2, wherein the radius is
smaller than a difference between the length of the tangent and the
spacing.
5. The sawtooth wire according to claim 2, wherein the radius is
substantially 0.07 mm.
6. The sawtooth wire according claim 1, wherein the spacing is
substantially 0.5 mm.
7. The sawtooth wire according to claim 1, wherein a ratio between
the spacing and a tooth tip spacing along the longitudinal extent
of the sawtooth wire from the tooth tip of a tooth of the row of
teeth to the tooth tip of an immediately adjacent tooth of the row
of teeth is substantially 5:17.
8. The sawtooth wire according to claim 1, wherein a tooth tip
spacing along the longitudinal extent of the sawtooth wire from the
tooth tip of a tooth of the row of teeth to the tooth tip of an
immediately adjacent tooth of the row of teeth is less than
approximately 2 mm.
9. The sawtooth wire according to claim 1, wherein the tangent and
a further tangent applied to the first segment at a location of the
associated tooth tip enclose a predetermined acute angle.
10. The sawtooth wire according to claim 9, wherein the
predetermined angle approximately is 30.degree.; lies between
30.degree. and 55.degree.; or is 55.degree..
11. The sawtooth wire according to claim 1, wherein the tooth back
of a respective one of the teeth comprises: a fifth segment which
adjoins the fourth segment of the respective preceding tooth of the
row of teeth and extends away from that fourth segment; and a sixth
segment which adjoins the fifth segment at the end thereof remote
from the fourth segment and extends towards the tooth tip of the
tooth; wherein the fifth and the sixth segments enclose with the
tooth side acute angles that are of different sizes to one
another.
12. The sawtooth wire according to claim 11, wherein the angle
between the fifth segment and the tooth side is larger than the
angle between the sixth segment and the tooth side.
13. The sawtooth wire according to claim 12, wherein the tooth back
of the tooth further comprises a seventh segment which adjoins the
sixth segment at an end thereof remote from the fifth segment, and
the seventh segment encloses with the tooth side an acute angle
that is larger than the angle between the sixth segment and the
tooth side.
14. The sawtooth wire according to claim 13, wherein the tooth back
further comprises an eighth segment which adjoins the seventh
segment at an end thereof remote from the sixth segment; and the
eighth segment encloses with the tooth side an acute angle that is
smaller than the angle between the seventh segment and the tooth
side.
15. The sawtooth wire according to claim 14, wherein a transition
region between at least two of the segments that are immediately
adjacent to one another and/or between the respective fourth
segment and the adjoining tooth back is or are continuous.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a U.S. National Stage Application of
International Patent Application No. PCT/EP2017/067085, filed Jul.
7, 2017, which claims benefit of German Patent Application No.
102016114622.6, filed Aug. 8, 2016.
TECHNICAL FIELD
The invention relates to a sawtooth wire for rolls of spinning room
preparation machines, such as carding machines, especially a
sawtooth wire for a cylinder.
BACKGROUND OF THE INVENTION
Such sawtooth wires are usually produced in the form of strip
material, optionally rolled up on transport reels and, for use,
applied in a helical or coil-like manner along an outer periphery
of a corresponding roll, for example a cylinder roll. Rolls formed
in that way are used for a wide variety of purposes. There are
cleaning rolls which are arranged to separate incoming fibre
material from impurities, such as, for example, cotton boll
material. Other sawtooth wires in turn are arranged to loosen and
parallelise fibres, as in the case, for example, of cylinder rolls
of carding machines. In the case of rolls positioned intermediately
in a processing line it is necessary to take up fibre material from
an upstream location and deliver it to a downstream location, and
this at the highest possible speed. This is the case, for example,
with cylinder rolls, which are provided to take up fibre material
from a licker-in roll and deliver it to a doffer roll. It has been
found in the case of the known sawtooth wires that too much fibre
material passes in the direction of the roll and is therefore not
delivered to the downstream location or is delivered only in an
inadequate amount. A lowest region between two teeth, usually the
transition region between the tooth front of one tooth and the
tooth back of the next tooth (referred to as the inter-tooth pace
hereinbelow) in the row of teeth of the sawtooth wire, has, seen
transversely with respect to the longitudinal extent of the
sawtooth wire, when stretched out, a spacing from a bearing surface
of the sawtooth wire on the roll that is sufficiently small to be
able to bend the sawtooth wire in order that the latter can be laid
around the associated roll, as described above, and thus applied to
that roll. During operation, fibres have a tendency to accumulate
in that transition region and therefore have the effect that fibre
material that is usable per se does not pass to further processing,
that is to say, for example, is not taken up by a doffing roll.
SUMMARY OF THE INVENTION
The object of the invention is to at least reduce that
disadvantage.
That object is achieved by the subject matter disclosed herein and
recited in the accompanying claims.
According to the invention there is provided a sawtooth wire which
is adapted to be applied in a helical or coil-like manner to a roll
of a spinning room preparation machine along an outer periphery of
the roll and substantially transversely with respect to the
rotational axis thereof. The sawtooth wire is in known manner
preferably produced in the form of strip material, for example
rolled onto a transport reel and, on application to a roll, applied
in a helical or coil-like manner to the outer periphery thereof.
The sawtooth wire has a tooth base having a bearing edge which
extends along the longitudinal extent of the sawtooth wire. That
bearing edge serves as the future bearing portion or contact
portion with the roll to which the sawtooth wire is to be applied.
Furthermore, the sawtooth wire has a row of teeth which is formed
on a tooth side of the tooth base remote from and opposite to the
bearing edge. If the sawtooth wire is stretched out, that is to say
is neither rolled up onto a transport reel nor applied to a roll,
it ideally runs along a straight line. In that state the row of
teeth extends along the longitudinal extent of the sawtooth wire
and comprises individual teeth. The teeth are arranged one after
the other in a row along the longitudinal extent of the sawtooth
wire in such a way that they project from the tooth side
substantially perpendicularly to the longitudinal extent of the
sawtooth wire. Each tooth has a tooth tip which points along the
longitudinal extent of the sawtooth wire and in the same direction
as the tooth tips of the other teeth of the row of teeth. That
direction can lie parallel to the tooth side or enclose an acute
angle therewith, that is to say point away from the tooth side.
Furthermore, each tooth has a tooth front. Starting from the
associated tooth tip of the respective tooth, the tooth front is
formed in such a way that in a first segment it extends at an acute
angle with respect to the tooth side towards an associated tooth
back of the tooth. The first segment merges into a concave second
segment which adjoins the end of the first segment remote from the
tooth tip. The end of the second segment remote from the first
segment points at an acute angle with respect to the tooth side in
the direction of the tooth side and away from the associated tooth
back. The second segment in turn merges into a third segment which
adjoins the end of the second segment remote from the first
segment, which third segment extends further towards the tooth side
and likewise away from the associated tooth back. The third segment
merges into a concave fourth segment which adjoins the end of the
third segment remote from the second segment, the end of which
fourth segment remote from the third segment points along the
longitudinal extent of the sawtooth wire and away from the
associated tooth back. The fourth segment then merges into a tooth
back of the subsequent tooth in the row of teeth, which tooth back
adjoins the end of the fourth segment remote from the third
segment, and therefore borders upon that tooth back. Furthermore,
in the afore-mentioned second segment there is a turning point at
which a second tangent applied to the second segment runs
perpendicularly to the tooth side. The length of the tangent from
the turning point to the tooth side is greater than or equal to
half the spacing, seen along the tangent (transversely with respect
to the longitudinal extent of the sawtooth wire), between the
associated tooth tip and the tooth side. The length of the tangent
therefore defines the spacing between the turning point and the
tooth side. This results in a tooth tip that is relatively low in
relation to the height dimension of the entire tooth. This has the
result that in the applied state of the sawtooth wire, that is to
say when the latter has been applied to an associated roll, fibre
material which is to be processed (for example carded) by means of
the teeth is no longer able to pass so easily into the inter-tooth
spaces and remain therein. In particular, the circumstance that the
fourth, concave segment merges directly into the tooth back of the
next tooth means that this transition point is very small. This has
the effect that it is scarcely possible for fibres to collect
therein but instead, on account of the rotational speed of the
associated roll, they are guided as it were immediately in the
direction of the second segment which has a rather high position in
relation to the surface of the roll. As a result, more fibre
material is supplied to further processing (for example in the form
of a drawing operation) than in the case of conventional sawtooth
wires. There is a reduction in waste and, in association therewith,
also in rejected material; the efficiency of a spinning room
preparation machine equipped with such a sawtooth wire is improved.
As a result, the fibres are guided in a higher position in relation
to the surface of the roll.
Preferably the ratio between the length of the second tangent, that
is to say the spacing of the turning point from the tooth side, and
the afore-mentioned spacing between the tooth tip and the tooth
side is 4:5. As a result, more fibre material passes into the
afore-mentioned third segment and from there can be conveyed in the
direction of the second segment close to the associated tooth tip
when the respective tooth, with the tooth tip to the front, is
guided past fibre material.
In the afore-mentioned cases the second segment can correspond to a
portion of a perimeter of an ellipse. As a result, a tooth front
that is free of sharp edges and therefore runs continuously is
formed in this region. The risk of fibres becoming stuck in this
region of the tooth front is averted or at least greatly
reduced.
Preferably the ellipse is a circle having a predetermined radius.
This is a geometric shape that is especially simple to produce.
The radius is preferably smaller than a difference between the
length of the second tangent and the afore-mentioned spacing
between the tooth tip and the tooth side. This enables the turning
point to be positioned very close to the associated tooth tip,
which helps further to reduce the waste.
The radius is in both cases preferably approximately 0.07 mm. This
has proved to be a very advantageous value in respect of fibre
uptake at the tooth front. In the context of the invention the term
"approximately" refers to production-related tolerances in relation
to the parameter in question, in this case the radius.
In the case of all sawtooth wires indicated above, the
afore-mentioned spacing between the tooth tip and the tooth side is
preferably approximately 0.5 mm. This is an especially suitable
value in order to be able to process fibres sufficiently.
In the case of the variants indicated above, the ratio between the
tip height, that is to say the spacing between the tooth side and
the tooth tip in a direction transverse with respect to the tooth
side, i.e. with respect to the longitudinal extent of the sawtooth
wire, and a tooth spacing along the longitudinal extent of the
sawtooth wire from the tooth tip of a tooth to the tooth tip of the
immediately adjacent tooth of the row of teeth, can be 5:17. This
results in an operationally very advantageous ratio between the
tooth height (height without the tooth base) and the spacing
between two immediately adjacent sawtooth wire teeth.
Such a tooth spacing, with or without maintenance of the ratio of
5:17, can be less than approximately 2 mm, preferably approximately
1.7 mm or 1.5 mm. Those lengths have proved to be especially
advantageous in respect of the fibres to be processed, especially
in respect of their length.
In the case of all the afore-mentioned sawtooth wires, the second
tangent and a first tangent applied to the first segment at the
location of the associated tooth tip preferably enclose a
predetermined acute angle.
That angle is preferably substantially at least 30.degree. and at
most 55.degree.. That angle range allows very efficient fibre
treatment.
In the case of each of the afore-mentioned sawtooth wires, the
tooth back of a tooth preferably comprises a fifth and a sixth
segment. The fifth segment adjoins the fourth segment of the
respective preceding tooth of the row of teeth and extends away
from that fourth segment. The sixth segment in turn then adjoins
the fifth segment at the end thereof remote from the fourth segment
and extends towards the tooth tip of the associated tooth. Finally,
the fifth and the sixth segments enclose with the tooth side acute
angles that are of different largest sizes to one another. That is
to say, the two segments slope upwards in the direction of the
tooth tip at different gradients to one another in relation to the
tooth side and thus make possible a kind of intermediate uptake of
fibres, but at least guidance of fibres in the direction of the
second segment of the respective tooth front immediately abutting
the tooth back in the row of teeth.
The largest angle between the fifth segment and the tooth side is
preferably smaller than the largest angle between the sixth segment
and the tooth side. The received fibres accordingly pass over the
sixth segment considerably more slowly, or not at all, in the
direction of the tooth side than is allowed by the fifth segment.
Fibres can thus be better conveyed into the processing process, for
example by centrifugal force, than would be possible with a segment
having only one gradient.
In addition or alternatively, the tooth back can further comprise a
seventh segment which adjoins the sixth segment at the end thereof
remote from the fifth segment. The seventh segment encloses with
the tooth side a largest acute angle that is larger than the
largest angle between the sixth segment and the tooth side.
Accordingly, a kind of step is formed in the region of the sixth
segment, although it does not necessarily run parallel to the tooth
side and therefore as it were horizontally. The tooth tip of the
associated tooth therefore projects further from the tooth side
than does the sixth segment and can accordingly be optimised for
extracting fibres, while the seventh segment and the second segment
of the respective tooth front bordering upon the sixth segment can
be optimised for conducting and discharging undesired fibres.
Preferably the tooth back additionally comprises an eighth segment
which adjoins the seventh segment at the end thereof remote from
the sixth segment. This eighth segment encloses with the tooth side
a largest acute angle that is smaller than the largest angle
between the seventh segment and the tooth side. This results in the
formation of a kind of hump between the tooth tip and the seventh
segment, which hump has an action similar to that of the sixth
segment in respect of the fibres.
In the case of each of the afore-mentioned sawtooth wires, the
transition region between at least two segments that are
immediately adjacent to one another and/or the transition region
between the respective fourth segment and the adjoining tooth back
can be continuous. That is to say, in an extreme case, between two
tooth tips that are arranged immediately adjacent to one another
there are no discontinuous transitions that could allow or promote
adhesion of fibres and accordingly have an adverse effect on the
action of the sawtooth wire.
BRIEF DESCRIPTION OF THE DRAWINGS
Further features and advantages of the invention will be apparent
from the following description of preferred embodiments. In the
drawings:
FIGS. 1a to 1c show various views of a sawtooth wire according to a
first embodiment of the invention,
FIG. 2 shows a sawtooth wire according to a second embodiment of
the invention,
FIG. 3 shows a sawtooth wire according to a third embodiment of the
invention,
FIG. 4 shows a sawtooth wire according to a fourth embodiment of
the invention and
FIG. 5 shows a sawtooth wire according to a fifth embodiment of the
invention.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1a shows a side view of a sawtooth wire 1 according to a first
embodiment of the invention when the sawtooth wire 1 is stretched
out. FIG. 1b shows the sawtooth wire 1 in section along a line A-A
in FIG. 1a. FIG. 1c in turn is a detail view on an enlarged scale
of the region delineated by a rectangle in FIG. 1a.
The sawtooth wire 1 has in a lower region in FIG. 1a and FIG. 1b a
tooth base 2, on the upper side of which a row of teeth is formed.
The row of teeth consists essentially of a plurality of teeth 3
arranged in a row one after the other.
The tooth base 2 has an underside which serves as a bearing edge 4
for the roll (not shown) to which the sawtooth wire 1 is to be
applied. The side of the tooth base 2 facing towards the teeth 3
forms a tooth side 5. As can be seen in FIG. 1b, the tooth side 5
is formed in such a way that, starting from the right-hand edge of
the tooth base 2, in the direction of the tooth 3 it merges into
the latter.
The teeth 3 have in known manner a tooth back 10 and a tooth front
20 which at one end meet at a tooth tip 6 of the respective tooth 3
and at the other end merge into the tooth front 20 of the
immediately preceding tooth 3 and the tooth back 10 of the
immediately following tooth 3, respectively.
The tooth base 2 is formed from a material which allows the
sawtooth wire 1 to be applied to an associated roll. For that
purpose it has a predetermined height h.sub.F
The tooth back 10 of the respective tooth 3 begins, starting from
the tooth front 20 of the preceding tooth 3, that is to say on the
left in FIG. 1a, with a segment 11 which slopes upwards in relation
to the tooth side 5 in the direction of the tooth tip 6. The
segment 11 runs at an acute angle with respect to the tooth side 5
towards the tooth tip 6. This segment 11 is adjoined by a segment
12 of the tooth back 10. The segment 12 has a relatively shallow
gradient in relation to the tooth side 5 or is even parallel
thereto. At its end remote from the segment 11, in this case the
right-hand end, the segment 12 merges into a next segment 13 which
has a steeper gradient than the segment 12 and, by way of example,
a shallower gradient than the segment 11. The segment 13, at its
end remote from the segment 12, in turn leads into what is then the
last segment 14 of the tooth back 10. The end of the segment 14
remote from the segment 13, in conjunction with an adjoining
segment 21 of the tooth front 20, forms the tooth tip 6.
Starting from the tooth tip 6, the segment 21 extends away from the
tooth tip 6 towards the tooth side 5 and towards the tooth back 10
of the same tooth 3. The segment 21, which runs substantially in a
straight line, merges at its end remote from the tooth tip 6 into a
segment 22 which in the example shown follows the perimeter of a
circle having a predetermined radius. The radius is by way of
example approximately 0.07 mm. The transition between the segments
21 and 22 is preferably continuous. This has the advantage that
fibres located therein are able to move past the tooth front 20
without the risk of becoming stuck.
At a lower end remote from the segment 21 the segment 22 merges
into a subsequent segment 23. In the example shown, the latter
segment is preferably formed as a straight segment similar to
segment 21. It extends towards the tooth side 5 and towards the
tooth back 10 of the subsequent tooth 3. This accordingly results
in a region that slopes downwards in relation to the tooth base 2.
At its end remote from the segment 22 the segment 23 merges into a
concave segment 24 which, at its end remote from the segment 23,
borders upon the tooth back 10 of the immediately subsequent tooth
3. The segment 24 has a minimum spacing from the tooth side 5 in
relation to the rest of the tooth 3, which spacing is sufficient
for laying the sawtooth wire 1 around a roll. For that purpose it
is necessary to deform the sawtooth wire 1 so that the bearing edge
4, which runs in a straight line in FIG. 1, rests tightly against
the outer periphery of the roll in all places. That minimum spacing
is preferably 0.1 mm.
At its point furthest to the left in FIG. 1 the segment 22 has a
spacing or a height h.sub.U perpendicular to the tooth side 5 that
is by way of example 0.5 mm. That point is therefore substantially
higher, in relation to the tooth side 5, than half the spacing, or
height h.sub.Z, of the tooth tip 6 from the tooth side 5. That
spacing accordingly corresponds to the length of a tangent
(perpendicular dot-dashed line) which can be applied at that
location and runs perpendicularly to the tooth side 5.
In the example shown, a tooth tip spacing a.sub.Z between the tooth
tips 6 of two immediately successive teeth, that is to say the
pitch, is less than approximately 2 mm, preferably approximately
1.7 mm or 1.5 mm with a tolerance of +0.06 mm to -0.03 mm.
A length I.sub.R of the respective tooth back 10 along the
longitudinal extent of the sawtooth wire 1, when stretched out,
that is to say along the tooth side 5, is by way of example more
than half the afore-mentioned tooth tip spacing a.sub.Z.
A tangent applied to the segment 21 in the region of the tooth tip
6 encloses a predetermined angle .alpha. with a line that is
perpendicular to the tooth side 5 and intersects the tooth tip 6.
In the example shown, the angle .alpha. is 55.degree. and is
accordingly exactly the same size as a corresponding angle between
that tangent and the afore-mentioned tangent applied to the turning
point in segment 22.
The tooth base 2 in FIG. 1b can of course also point towards the
left, so that the sawtooth wire 1 in this illustration is reflected
along a vertical line.
FIG. 2 shows a sawtooth wire 1 according to a second embodiment of
the invention. As can be seen, instead of four segments the tooth
back 10 here has only three segments 11-13. The segments 11-13 are
formed similarly to the segments 11-13 of the first embodiment;
segment 14 is absent. This has the result that a tangent applied to
the segment 13 and intersecting the tooth tip 6 encloses with the
tooth side 5 a larger acute angle .alpha. than in the case of the
first embodiment of the invention. The angle .alpha. is by way of
example identical dimensioned to the first embodiment.
FIG. 3 shows a sawtooth wire 1 according to a third embodiment of
the invention. In this case there are again likewise only three
segments 11-13 for the tooth back 10. The segment 11 is a concave
segment which, at its end remote from the previous tooth 3, merges
into a segment 12 which is formed by means of a plane that slopes
upwards in relation to the tooth side 5. The adjoining segment 13,
which extends towards the tooth tip 6 (without a reference sign in
this Figure), is preferably formed in the same way as the segment
14 of the first embodiment of the invention. That is to say, in
this case the segment 12 present in the first embodiment is absent.
Furthermore, the segment 21 has a steeper gradient than in the case
of the second embodiment. As a result, the angle .alpha. is
comparatively smaller and is 40.degree. in the example shown.
FIG. 4 shows a sawtooth wire 1 according to a fourth embodiment of
the invention. In contrast to the third embodiment, the segment 13
is relatively short.
FIG. 5 shows a sawtooth wire 1 according to a fifth embodiment of
the invention.
In this case the segment 13 is substantially longer than in the
case of the previous embodiments. This has the result that the
respective fibres spend a longer time in the upper region of the
sawtooth wire 1 and accordingly reduces the risk of fibres being
able to accumulate in the region of the segment 11.
In addition, the segment 24 is shorter than in the case of the
preceding embodiments.
The invention is not limited to the embodiments described
above.
Preferably, apart from the pairs of segments 13, 21 and 14, 21
forming the tooth tip 6, the segments 11-14, 21-24 in parts or as a
whole merge continuously into one another so that in the relevant
regions there are no discontinuous transitions that could promote
or allow sticking or adhesion of fibres.
The above-described shapes of the tooth front 20 and tooth back 10,
or of their segments 11-14; 21-24, can be combined with one another
or interchanged with one another in any desired way.
For example, the second and the fifth embodiments can be combined
with one another in such a way that the tooth backs 10 have a
terrace-like form.
The afore-mentioned radius in the case of segment 22 can also
assume a different value.
Segment 22 can also correspond to part of a perimeter of a
non-circular ellipse.
As a result, the invention provides a sawtooth wire 1 which is
suitable especially for cylinders and effectively prevents fibres
from being able to accumulate in the lower region, that is to say
in the region between the tooth front 20 and the tooth back 10 of
two immediately successive teeth 3. That is to say, the bulk of the
fibres are kept substantially further away from the tooth side 5
and closer to the respective tooth tip 6. This has the particularly
advantageous effect that the fibres can be taken up from the
sawtooth wire 1 by a complementary roll. Particularly in the case
of carding, the fibres can thus be better supplied to the doffing
roll, which improves the efficiency of the spinning room
preparation machine provided with the sawtooth wire 1. A further
advantage is that, by virtue of the sawtooth wire according to the
invention, the fibres can be better supplied to other elements
interacting with the sawtooth wire, such as flats and bars.
* * * * *